Enhanced cathodic ARC source for ARC plasma deposition

Abstract

An improved cathodic arc source and method of DLC film deposition with a carbon containing directional-jet plasma flow produced inside of cylindrical graphite cavity with depth of the cavity approximately equal to the cathode diameter. The generated carbon plasma expands through the orifice into ambient vacuum resulting in plasma flow strong self-constriction. The method represents a repetitive process that includes two steps: the described above plasma generation/deposition step that alternates with a recovery step. This step provides periodical removal of excessive amount of carbon accumulated on the cavity wall by motion of the cathode rod inside of the cavity in direction of the orifice. The cathode rod protrudes above the orifice, and moves back to the initial cathode tip position. The said steps periodically can be reproduced until the film with target thickness is deposited. Technical advantages include the film hardness, density, and transparency improvement, high reproducibility, long duration operation, and particulate reduction.

What is claimed is: 
     
       1. An apparatus for generation of directional carbon containing plasma flow in a cathodic arc source comprising:
 a cylindrical graphite cathode rod and an anode formed from of a plurality of spaced baffles, the cylindrical graphite cathode rod configured to generate the directional carbon, wherein the cylindrical graphite cathode rod and the anode are separated by an annular shield, and the cylindrical graphite cathode rod is within the annular shield, the annular shield further including an insulator tube with a thin wall graphite bushing inlaid inside of the insulator tube that coaxially surrounds at least a top surface of the cylindrical graphite cathode rod at an initial cathode tip position; 
 a bent solenoidal magnetic filter downstream of the cathodic arc source; and 
 a graphite cavity formed by extending both the annular shield and the thin wall graphite bushing beyond the top surface of the cylindrical graphite cathode rod at the initial cathode tip position, thereby creating a semi-confined space with a cavity orifice at least partially shaped identical to a shape of the top surface of the cylindrical graphite cathode rod. 
 
     
     
       2. The apparatus of  claim 1 , wherein the cathodic arc source further comprising a mechanism configured to selectively move the cylindrical graphite cathode rod inside of the annular shield along a rod axis in the direction of the cavity orifice protruding above the cavity orifice to a reference point and back to the initial cathode tip position. 
     
     
       3. The apparatus of  claim 2 , wherein the reference point is determined by a laser beam directed in between the baffles of the anode crossing the rod axis and a detector that is configured to control the laser beam indicates a drop of intensity when the cylindrical graphite cathode rod crosses a propagation line of the laser beam. 
     
     
       4. The apparatus of  claim 3 , further comprising a feedback system configured to pass a signal from the detector to a controller that controls the mechanism to selectively move the cylindrical graphite cathode rod and returns the cylindrical graphite cathode rod to the initial cathode tip position. 
     
     
       5. The apparatus of  claim 1 , wherein an arc discharge current of the cathodic arc source is higher than 600A. 
     
     
       6. The apparatus of  claim 1 , wherein the cavity orifice defines a diameter of approximately 5 mm to approximately 12 mm. 
     
     
       7. The apparatus of  claim 1 , wherein the anode defines a diameter that is approximately equal to a diameter of the cavity orifice. 
     
     
       8. The apparatus of  claim 1 , wherein a length of the anode does not exceed five times a diameter of the cavity orifice. 
     
     
       9. The apparatus of  claim 1 , wherein a diameter of the bent solenoidal magnetic filter is approximately two to four times a diameter of the cavity orifice. 
     
     
       10. The apparatus of  claim 1 , wherein a magnetic field strength inside of the bent solenoidal magnetic filter is approximately 1.5 to approximately 4 times a magnetic field strength sufficient to magnetize electrons. 
     
     
       11. The apparatus of  claim 1 , wherein a magnetic field strength in a central area of the bent solenoidal magnetic filter ranges between approximately 400 Gauss and approximately 1200 Gauss. 
     
     
       12. The apparatus of  claim 1 , wherein a current in the bent solenoidal magnetic filter solenoid is between approximately 400 Amps and approximately 800 Amps. 
     
     
       13. The apparatus of  claim 1 , wherein the cathodic arc source and the bent solenoidal magnetic filter are operated in a pulsed mode, and an arc pulse starts after a filter coil current pulse begins and ends before the filter coil current pulse ends.